As a nation, we are hooked. We now consume 679 million litres of energy drinks a year and sales of the beverage are worth more than £2 billion. It might help give us a jolt when tiredness hits, but what else do we know about the drinks and their impact on the body?

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Experts agree that having the occasional energy drink is unlikely to cause harm to most people, however drinking it excessively carries potential risks.

Generally speaking, adults shouldn’t have more than 400mg of caffeine a day, according to Dr Luke Powles, associate clinical director at Bupa UK. This equates to about four cups of coffee. For children and adolescents the recommended amount is far less (although there’s no official set guideline).

Pregnant women, meanwhile, should have less than 300mg per day, according to the World Health Organisation, which suggests high caffeine intake is associated with an increased risk of miscarriage and low birth weight.

Energy drinks tend to mainly impact the head and heart. “Our tolerance to caffeine and energy stimulants is different,” says Dr Powles. “However, if you’ve had too much, in the short term, your heart rate is likely to increase which can make you feel irritable, anxious, light-headed and give you palpitations.

“The stimulant effect can also cause headaches and make it difficult for you to fall asleep.”

Too much caffeine can also cause high blood pressure in some people, which can put strain on the kidneys and, in rare cases, convulsions and death could occur, says Dr Nitin Shori, a registered GP and medical director of the Pharmacy2u online doctor service.

There have been multiple past reports of people having fatal heart attacks and strokes in relation to high consumption of caffeine, including from energy drinks.

It’s not something you’d necessarily think about, but increased consumption of energy drinks can also impact the stomach, according to health experts. “Too much caffeine can upset acid in your stomach by relaxing the oesophagus (gullet), which can cause heartburn and irritate your stomach lining and gut,” explains Dr Powles. Due to the effects of caffeine on the intestines, it can also cause cramps, diarrhoea, nausea and vomiting in some people.

The liver is also not a fan, as consuming too much fat or sugar can contribute to fatty liver disease. Although this isn’t specific to energy drinks, Dr Powles notes.

But it’s not just caffeine consumption which poses a problem, too much sugar is also an issue when it comes to the beverages. Steve Preddy, a dentist at Bupa Dental Care, says, their sugar content is bad news for dental health: “Each time you have a sugary drink such as an energy drink, the levels of acid in your mouth rise, which raises the risk of tooth decay significantly. As the acid eats away at the enamel it can make your teeth thinner and weaker, which increases the likelihood of developing cavities.”

Drinking sugary drinks, such as energy drinks, could also lead to obesity, which in turn can be a factor in multiple health problems including diabetes, heart disease and cancer.

Dr Shariff Anwar, a registered GP at ZoomDoc, advises against drinking energy drinks with alcohol. “The combination of alcohol with energy drinks is associated with greater levels of intoxication and the propensity to drink more alcohol,” he says. “This is possibly because the stimulation from the energy drink offsets the sedation from the alcohol. It sounds like a positive on a night out, but knock-on effects are likely harmful.”